Effect of sample initial magnetic field on the metal magnetic memory NDT result

2018 ◽  
Vol 460 ◽  
pp. 285-291 ◽  
Author(s):  
Mahdi Moonesan ◽  
Mehrdad Kashefi
Keyword(s):  
Magnetic Field ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Initial Magnetic Field

Experimental Study of Magnetic Field Variation Induced in Ferromagnetic Materials

2013 ◽  
Vol 312 ◽  
pp. 402-405
Author(s):  
Yang Yong ◽  
Dong Sun ◽  
Jie Ji
Keyword(s):  
Magnetic Field ◽  
Plastic Region ◽  
Steel Specimen ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Magnetic Memory ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Metal Magnetic Memory ◽  
Stress Increase

The fatigue tests on 15CrMo steel specimen were carried out and the metal magnetic memory (MMM) signals were detected. The experiment shows that the magnetic signals of specimen contain the information of stress distribution in the material inside. Furthermore, the experimental results show that the magnetic signals increase initial while then decrease slightly with the stress increase from 0kN to 200kN. Though analysis the MMM signals induced by different tensile stress within the plastic region of the specimen, a simple model was derived. The experimental results are consistent with the calculated results based on the Jiles-Atherton model.

Characterization of Crack Initiation Life in Ferromagnetic Material by Metal Magnetic Memory Testing

2015 ◽  
Vol 817 ◽  
pp. 791-796
Author(s):  
Chang Liang Shi ◽  
Wei Xue Tang ◽  
Hao Zhan ◽  
Shi Yun Dong
Keyword(s):  
Magnetic Field ◽  
Crack Initiation ◽  
Normal Component ◽  
Ferromagnetic Material ◽  
Magnetic Memory ◽  
Memory Testing ◽  
Metal Magnetic Memory ◽  
Numerical Fitting ◽  
Crack Initiation Life ◽  
Metal Magnetic Memory Testing

In the geomagnetic field, stress can induce spontaneous magnetic signals in ferromagnetic materials, the method, named metal magnetic memory testing, can be potentially applied in estimating the fatigue life. In this paper, the normal component of magnetic field, Hp (y), was measured during dynamic tension test on the surfaces of ferromagnetic specimens with stress concentration factor of 5. The results indicated that the gradient of magnetic field intensity, K, was the key parameter to characterize crack initiation life. Then the numerical fitting of K and fatigue cycles were done under three level loads, 568.7MPa, 698.8MPa and 864.4MPa, meanwhile, a simple model was derived.

The State-of-the-Art Surveys for Application of Metal Magnetic Memory Testing in Remanufacturing

2011 ◽  
Vol 301-303 ◽  
pp. 366-372 ◽  
Author(s):  
Yuan Liang Zhang ◽  
Di Zhou ◽  
Peng Sen Jiang ◽  
Hong Chao Zhang
Keyword(s):  
Magnetic Field ◽  
Stress Concentration ◽  
Residual Life ◽  
Fatigue Cracks ◽  
Research Work ◽  
Creep Damage ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Comprehensive Survey ◽  
Chinese Scholars

Metal magnetic memory（MMM） testing has been used in the residual life prediction of remanufacturing cores. The MMM testing is one of the most promising nondestructive testing methods for achieving early diagnosis on micro defects of remanufacturing cores. This method can not only detect the traditional macro-cracks, but also identify the micro-damage caused by stress concentration. The principle of MMM testing works in the conditions that without requiring of the external exciting magnetic field, the magnetic field distribution of the inspection surface is scanned and measured by means of magnetic mutation signals to find the possible existence of stress concentration and location of micro-cracks. This paper presents a state-of-art survey about MMM testing mechanism and application of MMM method in Russia, Britain, China and the other countries. It includes the applications of this method in power station turbine blade damage detection by Russia scholars, evaluating the gear creep damage by Polish scholars and detecting the stress concentration districts of the train wheels damaged parts by Chinese scholars. The paper also reports that Chinese scholars developed methods of using MMM testing to characterize initiating and growing of fatigue cracks, and applied this method for prediction of residual life of remanufacturing cores. Based on the comprehensive survey, this paper points out further trends of the research work in the area. The paper also points out that microscopic physical mechanism of the MMM phenomenon and application of MMM testing in defining the manufacturability of remanufacturing cores should be further studied. Introduction

Correlation Between Stress Concentration Degree and Residual Magnetic Field

2016 ◽  
Author(s):  
Sheng Bao ◽  
Ashri Mustapha ◽  
Huangjie Lou
Keyword(s):  
Magnetic Field ◽  
Stress Concentration ◽  
Tensile Tests ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Residual Magnetic Field ◽  
Concentration Degree ◽  
Qualitative Relationship ◽  
Ferromagnetic Steels

In this research, the correlation between the stress concentration degree and the residual magnetic field (RMF) of ferromagnetic steels is investigated. Tensile tests were carried out to measure the RMF signals on the surface of steel specimens with different stress concentration degrees. The effectivity of the metal magnetic memory (MMM) technique in defective specimens was investigated in comparison with a non-defective specimen. Analysis of the qualitative relationship between the stress concentration degree and the RMF components was subsequently performed on two types of defective specimens. The qualitative correlation between the planar distributions of the RMF components and the stress concentration degree was further studied. It was validated that both the RMF signal and its planar distribution are effective in characterizing the stress concentration degree. The results obtained in this research will be a complement to the MMM technique.

Research on Features Extraction of Magnetic Field Sensor Based on Kalman Filter

2011 ◽  
Vol 396-398 ◽  
pp. 2240-2244
Author(s):  
Jian Sun ◽  
Wei Guo Lin
Keyword(s):  
Magnetic Field ◽  
Signal Processing ◽  
Kalman Filter ◽  
Wire Rope ◽  
Features Extraction ◽  
Magnetic Field Sensor ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Signal Noise ◽  
Field Sensor

In this paper,a method for wire rope non-destruction testing is proposed based on metal magnetic memory technology.The identification of metal magnetic memory signal depends on Signal Noise Ratio (SNR), but the sensor and signal processing determine the SNR.The unstabitily of environment and amplifier saturation can decrease the SNR, By signal processing, the necessity of realtime filtering for SNR is demonstrated.This paper utilizes Kalman filter to analysis the signal.The principle of Kalman filter is introduced The results shows us that the SNR and reliability of system is greatly improved with this method.

Stress State Detection Based on Metal Magnetic Memory Theory

2005 ◽  
Author(s):  
HaiYan Xing ◽  
RiXin Wang ◽  
MinQiang Xu ◽  
JiaZhong Zhang
Keyword(s):  
Magnetic Field ◽  
Stress State ◽  
Carbon Steel ◽  
Material Strength ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Low Carbon ◽  
Medium Carbon ◽  
Field Density ◽  
Critical Damage

The metal magnetic memory (MMM) technology, a new nondestructive evaluation (NDE) method, is an effective means for early damage prediction. However, there is so much work to do, such as the relationship between the magnetic field density and stress state. This paper aims at finding out MMM signal characteristics of critical damage stress state by tension experiments. Comparisons between MMM testing and traditional NDE method are presented. The principle of MMM testing is investigated. Different materials, low carbon steal X70 and medium carbon Q235B, are detected on-line and off-line respectively. It is found that MMM signal rules are gradually increasing up to fluctuating on the verge of yield and sharp changing of magnetic polarity on the verge of fracture. With the increase in material strength, magnetic field density of low carbon steel X70 is lower than that of medium carbon steel Q235B. This offers fundamental study for the quantitative MMM testing of critical damage stress state.

Stress Concentration Positions Determination of Ferromagnetic Material Based on Magnetic Test Method

2009 ◽  
Vol 417-418 ◽  
pp. 865-868
Author(s):  
Feng Yun Yu ◽  
Jing Chong Zhang
Keyword(s):  
Magnetic Field ◽  
Stress Concentration ◽  
Spontaneous Magnetization ◽  
Tensile Load ◽  
Test Point ◽  
Test Method ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Magnetic Intensity ◽  
The Magnetic Field

The magnetic field of ferromagnetic components under service load and geomagnetic field increases is induced by the residual magnetic induction and spontaneous magnetization. The stress concentration positions can be determination by detecting the magnetic field and the fracture can be avoided. The magnetic intensities of the demagnetized samples are tested by metal magnetic memory test method. By tensile test, the relationship between the magnetic memory signals and tensile load is studied, and the metal magnetic memory characteristics of the demagnetized samples under condition that the load keeps a fixed value are obtained. The test result indicates that the magnetic intensities of the samples change greatly after demagnetized; the change of the magnetic intensity of each test point are much different with different tensile displacement; in the later period of hardening phase and necking phase, the magnetic intensity about the side of the stress concentration positions increases along with the increasing of tensile displacement, however that of the other side decreases, that is the gradient of Fracture position increases obviously. Basing on this result by testing the parts of components emphatically where the fatigue failure and breakdown appear easily, the abrupt accident can be avoided.

Monitoring the Petrol Engine Oil Viscosity: Investigation of the Capability of the Metal Magnetic Memory Technology

2014 ◽  
Vol 663 ◽  
pp. 453-458
Author(s):  
Othman Inayatullah ◽  
Wang Siow Chin ◽  
Nordin Jamaludin ◽  
Shahrum Abdullah ◽  
Azli Ariffin
Keyword(s):  
Magnetic Field ◽  
Petrol Engine ◽  
Engine Oil ◽  
Field Energy ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Oil Viscosity ◽  
Maintenance Schedule ◽  
Magnetic Field Energy ◽  
The Magnetic Field

An engine lubrication system is one of the main factors which influence engine life span, and it can be easily determined based on the viscosity of the engine oil. The current and common technology for monitoring and the determination of the engine oil viscosity using the oil analysis method is found to be uneconomical and ineffective. On the same vein, this paper presents an investigation of the capability of the Metal Magnetic Memory (MMM) technology in the processes of monitoring and detecting the variation of petrol engine lubricant viscosity via in-situ operation. A few investigations were conducted on a Robin Engine 126 cc EX 13D single cylinder of four strokes with water cooling. One multi-grade engine lubricant oil condition has been put to the test; namely, SAE 15W-40. During the investigation of the petrol engine oil viscosity, the magnetic field signal is captured when the engine oil in-service age is 0 km (fresh oil), 250 km, 500 km, 750 km and 1,000 km, with the crankshaft rotational speed of 2500 rpm at three different locations such as at the Bottom Dead Centre (BDC), oil sump A (engine oil inlet), and oil sump B. The lubrication condition in the petrol engine is successfully monitored based on the magnetic field signatures generated by the interaction between the piston surface and the layer of the lubricant during the time when the engine was in operation. The generated MMM signatures were captured using a type 2 scanning device with two ferroprobe sensors and a length measuring sensor and recorded by the TSC-3M-12 type device. The waveform signatures captured were displayed as length domain signal and then were analysed using the MATLAB software to determine the magnetic field energy (EH). In addition, the real viscosity value at room temperature was determined using the Haake Viscotester 6 L, each time after the magnetic field signal was captured. The results of these studies have shown that the magnetic field energy (EH) is inversely proportional to engine oil viscosity. Finally, the MMM technology can be utilised in promoting economic development and effective planning of the maintenance schedule of the petrol engine oil.

Research on the Attenuation Law of Metal Magnetic Memory Testing Signal

2014 ◽  
Vol 668-669 ◽  
pp. 981-984
Author(s):  
Yuan Liang Zhang ◽  
Yan Lv ◽  
Hao Zhang ◽  
Jin Long Wang ◽  
Gui Jie Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Memory ◽  
Memory Testing ◽  
Static Tension ◽  
Metal Magnetic Memory ◽  
Surface Magnetic Field ◽  
Signal Value ◽  
Testing Signal ◽  
Metal Magnetic Memory Testing ◽  
Normal Magnetic Field

In order to clear the timeliness issues of metal magnetic memory signal value after unloading, we conduct some static tension experiments on some specimens in materials of KMN, which is commonly used in centrifugal compressors? Furthermore, we analyze the specimen, which is prefabricated artificial defects, on the surface normal magnetic field strength decay law with EMS-2003, the intelligent magnetic memory tester. The results show that: the surface magnetic field signal value is reduced by time after unloading, in other words it has certain timeliness.

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